Automatic lathe, and method for controlling the same and device for controlling the same

ABSTRACT

A method for controlling an automatically operated lathe, provided with at least one spindle and at least one tool rest, includes the following steps. First, each of a plurality of transfer position data required in a sequence of machining programs in connection with at least one spindle and at least one tool rest is provided in a form of a cam-reference data directing a transfer position as a function of a cam rotation quantity. A plurality of pulse-train generating sources, each of which generates any pulse train, is also provided. Next, with regard to each of the plural transfer position data, a pulse-train generating source for generating a pulse train defining the cam rotation quantity as one component of the cam-reference data is designated, with the pulse-train generating source being selected from the plural pulse-train generating sources. Then, each of the plural transfer position data provided in the form of the cam-reference data is processed by using the pulse train generated through the pulse-train generating source as designated, so as to control a relative feed motion between at least one spindle and at least one tool rest in the sequence of machining programs.

TECHNICAL FIELD

The present invention relates to an automatically operated lathe andmethod for controlling the same.

BACKGROUND ART

A turning machine tool capable of performing an automatic turningprocess (referred generically to as an automatically operated lathe inthis specification) may automatically carry out various turningprocesses in sequence or, if necessary, simultaneously, by causing afeed motion of various tools carried on a tool rest relative to abar-shaped or disk-shaped workpiece to be machined, which is securelyheld in a spindle. Recently, an automatically operated lathe of a type(called an electronic-cam type) controlling a relative feed motionbetween a workpiece or spindle and a tool or tool rest by a machiningcommand using a cam-reference data for successively directing toolpositions as a function of cam rotation angles, has been provided.

In the electronic-cam type automatically operated lathe, an electricoperating command following a predetermined cam curve is used, in placeof a mechanical operation of a cam used in a traditional cam-installedautomatic lathe, to automatically control a relative feed motion betweenthe spindle and the tool rest. Accordingly, the electronic-cam typeautomatically operated lathe is capable of advantageously performing arelatively simple machining sequence in a short time, due to respectivemotions of tools carried on plural tool rests, which follow individualcam curves in a way similar to the conventional cam-installed automaticlathe. In particular, according to such an electronic-cam system, it isnot necessary to provide many types of mechanical cams corresponding tothe configurations of machined products, and it is possible tosignificantly reduce time and labor required for an initial set-up,which permits various kinds of products to be manufactured in very highproductivity in comparison with the conventional cam-installed automaticlathe.

Also, in the electronic-cam type automatically operated lathe, even whenthe machine structure thereof is provided with a plurality of controlaxes along which the spindle and the tool rest are relatively operated,it is possible to prepare cam diagrams for the respective control axeson a common reference (i.e., a cam rotation angle), which advantageouslymakes it easier to program a synchronizing command of the control axes.Moreover, the operation of the control axes is individually and freelycontrollable, so that, in the case where various machining processes aresuccessively performed by using plural tools, it is made easier tooperate the tools so as to overlap in time, and thereby, it is possibleto significantly reduce the time required for the entire machiningprocess (i.e., one machining cycle) of the workpiece to be machined.Contrary to this, in the conventional NC lathe, it is generallydifficult, from a viewpoint of machine and control structure, to performa machining process of one tool until another tool reaches a stand-byposition after finishing the machining process thereof, and thereby, thetime required for one machining cycle inevitably includes the idle timeof tools.

In the above-described electronic-cam type automatically operated lathe,the cam rotation angle as a reference for preparing the cam diagrams maybe defined on the basis of a rotational frequency of the spindle. Thatis, a predetermined rotational frequency of the spindle is defined tocorrespond to a single rotation (360 degrees) of the cam, and toolpositions are successively directed corresponding to the rotationalfrequencies of the spindle, so as to control the operation of therespective control axes. According to this structure, it is possible toindividually control the operation of the plural control axes on thebasis of a common reference defined by the rotational frequency of thespindle (normally, the rotational frequency of the drive source of thespindle) that is a mechanically operative component of the automaticallyoperated lathe.

However, in this structure, the operation of the control axes cannot becontrolled during a period when the spindle does not rotate. Therefore,it is difficult, in the automatically operated lathe performing anelectronic-cam control on the basis of the rotational frequency of thespindle, to carry out, for example, a secondary process (e.g., a cuttingprocess by a rotary tool) during a period when the spindle does notrotate, which can be carried out by a conventional multifunctionalnumerically-controlled (NC) lathe.

Also, the rotational frequency of the spindle may be varied, in general,due to a machining load applied to the spindle by, e.g., a cutting forceduring the machining process. In particular, in the structure wherein adrive force from a spindle drive source is transmitted to the spindlethrough a transmission mechanism such as a belt/pulley, the rotationalfrequency of the spindle drive source tends to become different from theactual rotational frequency of the spindle, when a slip is caused in thetransmission mechanism by the machining load. In this case, in anelectronic-cam control on the basis of the rotational frequency of thespindle drive source, the spindle and the tool rest are operated toperform the relative feed motion in accordance with the rotationalfrequency of the spindle drive source irrespective of the actualmachining progress of the workpiece, which may cause deterioration ofthe machining accuracy.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an automaticallyoperated lathe capable of controlling a relative feed motion between aspindle and a tool rest in an electronic-cam system, and capable ofexerting multifunctional properties for performing a secondary processduring a period when a spindle does not rotate, as well as to provide amethod for controlling such an automatically operated lathe.

Another object of the present invention is to provide an automaticallyoperated lathe capable of controlling a relative feed motion between aspindle and a tool rest in an electronic-cam system, and capable ofperforming a high precision machining without being influenced from thevariation of the rotational frequency of the spindle, as well as toprovide a method for controlling such an automatically operated lathe.

To achieve the above object, the present invention provides in oneaspect thereof a method for controlling an automatically operated latheprovided with at least one spindle and at least one tool rest,comprising providing each of a plurality of transfer position datarequired in a sequence of machining programs in connection with the atleast one spindle and the at least one tool rest in a form of acam-reference data directing a transfer position as a function of a camrotation quantity; providing a plurality of pulse-train generatingsources, each of which generates any pulse train; designating, withregard to each of the plurality of transfer position data, a pulse-traingenerating source for generating a pulse train defining the cam rotationquantity as one component of the cam-reference data, the pulse-traingenerating source being selected from the plurality of pulse-traingenerating sources; and processing each of the plurality of transferposition data provided in the form of the cam-reference data by usingthe pulse train generated through the pulse-train generating source asdesignated, to control a relative feed motion between the at least onespindle and the at least one tool rest in the sequence of machiningprograms.

In the preferred embodiment, the method for controlling is provided,wherein the at least one spindle and the at least one tool rest arecapable of performing a relative feed motion along a plurality ofcontrol axes, and wherein the step of designating the pulse-traingenerating source includes designating the pulse-train generating sourcewith regard to each of the plurality of transfer position data inrelation to each of the plurality of control axes.

In the preferred embodiment, the method for controlling is provided,further comprising a step of designating a time-series allocation of theplurality of transfer position data in the sequence of machiningprograms, wherein the step of processing the transfer position dataincludes processing, in accordance with the time-series allocation asdesignated, each of the plurality of transfer position data provided inthe form of the cam-reference data.

It is advantageous that the method further comprises a step of showing,in a form of a displacement diagram, each of the plurality of transferposition data provided in the form of the cam-reference data.

In this arrangement, the step of designating the pulse-train generatingsource may include designating, in association with the displacementdiagram, the pulse-train generating source with regard to each of theplurality of transfer position data.

Also, the method for controlling may be provided, further comprising astep of designating a time-series allocation of the plurality oftransfer position data in the sequence of machining programs on thedisplacement diagram, wherein the step of processing the transferposition data includes processing, in accordance with the time-seriesallocation as designated on the displacement diagram, each of theplurality of transfer position data provided in the form of thecam-reference data.

In this arrangement, a structure may be provided, wherein the at leastone spindle and the at least one tool rest are capable of performing arelative feed motion along a plurality of control axes, and wherein thestep of designating the time-series allocation includes designating, onthe displacement diagram, a synchronization between the plurality oftransfer position data for respectively operationally controlling theplurality of control axes.

The plurality of pulse-train generating sources may include aspindle-pulse generating source generating a pulse train correspondingto a rotation of the at least one spindle.

Also, the plurality of pulse-train generating sources include anoutside-pulse generating source generating a pulse train irrespective ofan operation of the automatically operated lathe.

The present invention provides in one aspect thereof an automaticallyoperated lathe, comprising a lathe bed; at least one spindle mounted onthe lathe bed; at least one tool rest mounted on the lathe bed; acontrol device for controlling an operation of the at least one spindleand the at least one tool rest on the lathe bed; and a plurality ofpulse-train generating sources, each of which generates any pulse train;the control device including an input section permitting entering ofeach of a plurality of transfer position data required in a sequence ofmachining programs in connection with the at least one spindle and theat least one tool rest in a form of a cam-reference data directing atransfer position as a function of a cam rotation quantity, andpermitting a designation of a pulse-train generating source forgenerating a pulse train defining the cam rotation quantity as onecomponent of the cam-reference data, with regard to each of theplurality of transfer position data, the pulse-train generating sourcebeing selected from the plurality of pulse-train generating sources; anda processing section processing each of the plurality of transferposition data entered through the input section in the form of thecam-reference data by using the pulse train generated through thepulse-train generating source designated through the input section, tothereby generate a control signal for controlling a relative feed motionbetween the at least one spindle and the at least one tool rest in thesequence of machining programs.

In the preferred embodiment, an automatically operated lathe isprovided, wherein the at least one spindle and the at least one toolrest are capable of performing a relative feed motion along a pluralityof control axes on the lathe bed, and wherein the input section of thecontrol device permits a designation of the pulse-train generatingsource with regard to each of the plurality of transfer position data inrelation to each of the plurality of control axes.

In the preferred embodiment, an automatically operated lathe isprovided, wherein the input section of the control device permits andesignation of a time-series allocation of the plurality of transferposition data in the sequence of machining programs, and wherein theprocessing section of the control device processes, in accordance withthe time-series allocation designated through the input section, each ofthe plurality of transfer position data entered in the form of thecam-reference data through the input section.

It is advantageous that the control device further includes a displaysection displaying, in a form of a displacement diagram, each of theplurality of transfer position data entered through the input section inthe form of the cam-reference data.

In this arrangement, it is preferred that the input section of thecontrol device permits a designation of the pulse-train generatingsource with regard to each of the plurality of transfer position data,in association with the displacement diagram displayed in the displaysection.

Also, the structure may be provided, wherein the input section of thecontrol device permits a designation of a time-series allocation of theplurality of transfer position data in the sequence of machiningprograms on the displacement diagram displayed in the display section,and wherein the processing section of the control device processes, inaccordance with the time-series allocation as designated on thedisplacement diagram, each of the plurality of transfer position dataentered in the form of the cam-reference data through the input section.

In this arrangement, it is preferred that the at least one spindle andthe at least one tool rest are capable of performing a relative feedmotion along a plurality of control axes on the lathe bed, and that theinput section of the control device permits a designation of asynchronization between the plurality of transfer position data forrespectively operationally controlling the plurality of control axes, onthe displacement diagram displayed in the display section.

The plurality of pulse-train generating sources may include aspindle-pulse generating source generating a pulse train correspondingto a rotation of the at least one spindle.

Also, the plurality of pulse-train generating sources may include anoutside-pulse generating source generating a pulse train irrespective ofan operation of the automatically operated lathe.

The present invention provides in one aspect thereof a control devicefor use in an automatically operated lathe provided with at least onespindle and at least one tool rest, comprising an input sectionpermitting an entering of each of a plurality of transfer position datarequired in a sequence of machining programs in connection with the atleast one spindle and the at least one tool rest in a form of acam-reference data directing a transfer position as a function of a camrotation quantity, and permitting a designation of a pulse-traingenerating source for generating a pulse train defining the cam rotationquantity as one component of the cam-reference data, with regard to eachof the plurality of transfer position data, the pulse-train generatingsource being selected from a plurality of pulse-train generating sourcesas previously provided; and a processing section processing each of theplurality of transfer position data entered through the input section inthe form of the cam-reference data by using the pulse train generatedthrough the pulse-train generating source designated through the inputsection, to thereby generate a control signal for controlling a relativefeed motion between the at least one spindle and the at least one toolrest in the sequence of machining programs.

In the preferred embodiment, the control device is provided, wherein theinput section permits an designation of a time-series allocation of theplurality of transfer position data in the sequence of machiningprograms, and wherein the processing section processes, in accordancewith the time-series allocation designated through the input section,each of the plurality of transfer position data entered in the form ofthe cam-reference data through the input section.

It is advantageous that the device further comprises a display sectiondisplaying, in a form of a displacement diagram, each of the pluralityof transfer position data entered through the input section in the formof the cam-reference data.

In this arrangement, it is preferred that the input section permits adesignation of the pulse-train generating source with regard to each ofthe plurality of transfer position data, in association with thedisplacement diagram displayed in the display section.

Also, a structure may be provided, wherein the input section permits adesignation of a time-series allocation of the plurality of transferposition data in the sequence of machining programs on the displacementdiagram displayed in the display section, and wherein the processingsection processes, in accordance with the time-series allocation asdesignated on the displacement diagram, each of the plurality oftransfer position data entered in the form of the cam-reference datathrough the input section.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description ofpreferred embodiments with reference to the attached drawings, in which:

FIG. 1 is a flow chart showing the procedure of a method for controllingan automatically operated lathe, according to an embodiment of thepresent invention;

FIG. 2A is a displacement diagram representing one example of acam-reference data used in the controlling method of FIG. 1;

FIG. 2B is a displacement diagram representing one example of anothercam-reference data used in the controlling method of FIG. 1;

FIG. 3A is a displacement diagram representing composed cam-referencedata of FIGS. 2A and 2B;

FIG. 3B is another displacement diagram representing composedcam-reference data of FIGS. 2A and 2B;

FIG. 4 is a block diagram showing a system for specifying a cam-rotationquantity of the cam-reference data used in the controlling method ofFIG. 1;

FIG. 5 is a block diagram showing another system for specifying acam-rotation quantity of the cam-reference data used in the controllingmethod of FIG. 1;

FIGS. 6A and 6B are illustrations of display screen pictures, showing aprocedure for directing a data interruption information in thecontrolling method of FIG. 1;

FIG. 7 is a schematic illustration showing the constitution of anautomatically operated lathe, according to one embodiment of the presentinvention, which can perform the controlling method of FIG. 1;

FIG. 8 is a block diagram showing the constitution of a control deviceinstalled in the automatically operated lathe of FIG. 7;

FIG. 9 is an enlarged front view of a first tool rest mounted on theautomatically operated lathe of FIG. 7;

FIG. 10 is an enlarged front view of a second tool rest mounted on theautomatically operated lathe of FIG. 7;

FIG. 11 is a schematic illustration showing an example of a machiningsequence performed on the automatically operated lathe of FIG. 7;

FIG. 12 is a displacement diagram representing cam-reference data fortwo control axes used in the machining sequence of FIG. 11;

FIG. 13 is a displacement diagram representing cam-reference data foranother control axis used in the machining sequence of FIG. 11;

FIG. 14 is a displacement diagram representing cam-reference data forthe other two control axes used in the machining sequence of FIG. 11;

FIG. 15 is a displacement diagram representing cam-reference data forthe other one control axes used in the machining sequence of FIG. 11;

FIG. 16 is a compound-axis displacement diagram composed from thedisplacement diagrams of FIGS. 12 and 14;

FIG. 17 is a compound-axis displacement diagram representing a stateafter the compound-axis displacement diagram of FIG. 16 is interruptedby the displacement diagrams of FIGS. 13 and 15; and

FIG. 18 is a displacement diagram representing a state where thecompound-axis displacement diagram of FIG. 16 is incompletely prepared.

BEST MODES FOR CARRYING OUT THE INVENTION

With reference to the drawings, FIG. 1 is a flow chart showing theprocedure of a controlling method of an automatically operated lathe,according to an embodiment of the present invention, and FIGS. 2A to 3Bare displacement diagrams representing one example of plural transferposition data used in this controlling method.

The controlling method of an automatically operated lathe, according tothe present invention, is constituted for controlling a relative feedmotion between a spindle and a tool rest, which is carried out inaccordance with a sequence of machining programs for cutting andmachining one product from a workpiece to be machined, in anautomatically operated lathe provided with at least one spindle and atleast one tool rest. First, as shown in FIG. 1, each of a plurality oftarget or transfer position data (i.e., travel locus data) required inthe sequence of machining programs in connection with at least onespindle and at least one tool rest is provided in the form of acam-reference data directing a transfer position as a function of a camrotation quantity (a step S1). Also, a plurality of pulse-traingenerating sources, each of which generates any pulse train, areprovided (a step S2).

Next, a pulse-train generating source for generating a pulse traindefining the cam rotation quantity as one component of the cam-referencedata is designated, with regard to each of the plural transfer positiondata provided in the step S1, by selecting the pulse-train generatingsource from the plural pulse-train generating sources provided in thestep S2 (a step S3). Then, each of the plural transfer position dataprovided in the step S1 is processed by using the pulse train generatedthrough the pulse-train generating source designated in the step S3 (astep 54), and a relative feed motion between at least one spindle and atleast one tool rest in the sequence of machining programs is controlled(a step S5).

In the case where at least one spindle and at least one tool rest in theautomatically operated lathe are capable of performing the relative feedmotion along a plurality of control axes on a lathe bed, the step fordesignating the pulse-train generating source (the step S3) includesdesignating the pulse-train generating source with regard to each of theplural transfer position data in relation to each of the plural controlaxes.

The cam-reference data provided in the step S1 as described isconstituted so that a predetermined operation quantity obtained from anymechanically operative component in the automatically operated latheand/or a predetermined signal quantity obtained from a signal generatingcomponent outside the automatically operated lathe is defined tocorrespond to the single rotation of the cam, and that the transferpositions of the spindle or the tool rest are successively directed onthe basis of the operation quantity and/or the signal quantity.Therefore, it is satisfied that the plural pulse-train generatingsources provided in the step S2 are capable of respectively convertingsuch an operation quantity obtained from any mechanically operativecomponent in the automatically operated lathe and/or a signal quantityobtained from a signal generating component outside the automaticallyoperated lathe into a form of any pulse trains and capable of outputtingthe pulse trains. It will be appreciated that the definition of the camrotation quantity as one component of the cam-reference data by thepulse train, in the way described above, facilitates a data processingin step S4.

In the step S3, in order to ensure that various processes in thesequence of machining programs are capable of being performed under aso-called electronic-cam type control, a pulse-train generating sourcefor generating a pulse train for processing the cam-reference data isdesignated, with regard to each of the plural transfer position datacorresponding to the respective processes, by suitably selecting thepulse-train generating source from the plural pulse-train generatingsources as described. Then, in the steps S4 and S5, the relative feedmotions between the spindle and the tool stock in the various processesare surely controlled in the electronic-cam system by effectively usingthe pulse train generating sources as respectively designated.

According to this arrangement, a so-called electronic-cam type controlis carried out in all of the various processes in the sequence ofmachining programs, which permits the operation of the plural controlaxes in the automatically operated lathe to be individually and freelycontrolled, and therefore, the idle time of tools is easily eliminatedand the time required for one machining cycle is effectively reduced incomparison with a conventional NC lathe. Moreover, in each process, itis possible to prepare the displacement diagrams (or cam diagrams)regarding the respective control axes on the common reference (i.e., thecam rotation quantity), which facilitates the programming of asynchronizing command of the control axes.

In particular, according to the present invention, it is possible tosurely perform the various processes in the sequence of machiningprograms under the electronic-cam type control by effectively using thepulse-train generating sources respectively designated with regard toeach of the plural transfer position data corresponding to therespective processes. Therefore, remarkable effects are obtainable inwhich it is possible, for example, to surely perform, on the basis ofthe cam-reference data, the secondary process (e.g., a cutting processby a rotary tool) performing while the spindle is halted, by designatingthe desired pulse-train generating source which converts an operationquantity obtained from a mechanically operative component other than thespindle and/or a signal quantity obtained from a signal generatingcomponent outside the automatically operated lathe into a form of anypulse train and outputs the pulse train.

In the above-described control flow according to the present invention,a step for designating the time-series allocation of the plural transferposition data in the sequence of machining programs may be additionallyprovided, in association with the step S3 of designating the pulse-traingenerating source. According to this step, it is possible to arrange, inthe most suitable order, various processes corresponding to the pluraltransfer position data for which the desired pulse-train generatingsources are respectively designated. Accordingly, in the steps S4 andS5, each of the plural transfer position data provided in the form ofthe cam-reference data is processed in accordance with the time-seriesallocation as designated, whereby the relative feed motion between thespindle and the tool rest is controlled, in each of the variousprocesses arranged in the most suitable order, in a way as to followthis order.

Also, in the above-described control flow according to the presentinvention, a step for showing, in the form of a displacement diagram (acam diagram) representing a locus of transfer positions (e.g., a toolpath), each of the plural transfer position data provided in the form ofcam-reference data, may be added in association with the step S1 forproviding the transfer position data. In this case, it is advantageousto permit the step S3, of designating the pulse-train generating source,to designate, in association with the displacement diagram, thepulse-train generating source with regard to each of the plural transferposition data. It is also advantageous to permit the above-describedstep, of designating the time-series allocation of the plural transferposition data in the sequence of machining programs, to designate thetime-series allocation on the shown displacement diagram.

FIGS. 2A and 2B are displacement diagrams (or cam diagrams) respectivelyrepresenting examples of two different transfer position data providedin the form of cam-reference data. In this respect, a first pulse-traingenerating source generating a pulse train for processing the firstcam-reference data shown in FIG. 2A is designated in association withthe displacement diagram of FIG. 2A. Also, a second pulse-traingenerating source generating a pulse train for processing the secondcam-reference data shown in FIG. 2B is designated in association withthe displacement diagram of FIG. 2B. In these examples, most of thesequence of machining programs (Q0 to QE) is carried out on the basis ofthe first cam-reference data, and only a specific program (Q1 to Q2) iscarried out on the basis of the second cam-reference data.

Then, the time-series allocation of these two transfer position data maybe designated on either one of the displacement diagrams. In theillustrated examples, a location where the second cam-reference datarepresented in the displacement diagram of FIG. 2B interrupts isdesignated on the displacement diagram of FIG. 2A. FIG. 3A shows oneexample of a composite displacement diagram representing the transferposition data in the sequence of machining programs, in a state afterthe interruption by the cam-reference data associated with the differentpulse-train generating source is designated.

Therefore, in this example of a machining sequence, during a conditionwhere the cam rotation quantity advances from Q0 to Q1, the relativefeed motion between the spindle and the tool rest is controlled on thebasis of the first cam-reference data processed by using the firstpulse-train generating source, and, during a condition where the camrotation quantity advances from Q1 to Q2, the relative feed motionbetween the spindle and the tool rest is controlled on the basis of thesecond cam-reference data processed by using the second pulse-traingenerating source. Thereafter, during a condition where the cam rotationquantity advances from Q2 to QE, the relative feed motion between thespindle and the tool rest is controlled again on the basis of the firstcam-reference data. In this manner, one machining cycle is completed.

In the above machining sequence example, if the control axisoperationally controlled on the basis of the first cam-reference data isdifferent from the control axis operationally controlled on the basis ofthe second cam-reference data, it is possible to allocate thedisplacement diagram representing the second cam-reference datairrespective of the transfer position P1 at the interrupted location onthe displacement diagram of the first cam-reference data, as shown inFIG. 3A. Contrary to this, if the interruption by the secondcam-reference data to the first cam-reference data is performed on thesame control axis, the displacement diagram representing the secondcam-reference data is allocated in such a manner as to continue thetransfer position P1 at the interrupted location on the displacementdiagram of the first cam-reference data, as shown in FIG. 3B.

In the above machining sequence example, the first pulse-traingenerating source may be constructed from, for example, a spindle-pulsegenerating source generating a pulse train corresponding to a rotationof at least one spindle of the automatically operated lathe. Also, thesecond pulse-train generating source may be constructed from, forexample, a tool-pulse generating source generating a pulse traincorresponding to a rotation of the rotary tool carried on at least onetool rest of the automatically operated lathe.

For example, as shown in FIG. 4, an encoder E provided in a spindlemotor M1 may be used as the spindle-pulse generating source. In thiscase, it is advisable that a control device C installed in theautomatically operated lathe is constituted to use a pulse train outputfrom the encoder E for a spindle rotation control as a feedback data aswell as for processing the cam-reference data in the above-describedelectronic-cam control. In this arrangement, the control device Coperates and processes the transfer positions directed through thecam-reference data by using the pulse train acquired from the encoder E,and outputs a transfer command based thereon so as to control theoperation of a control axis motor M2. In the same manner, but notillustrated, an encoder provided in a drive motor for a tool rotationmay be used as the tool-pulse generating source.

Incidentally, in the structure wherein a drive force from the spindlemotor M1 is transmitted to the spindle through a transmission mechanismsuch as a belt/pulley, the rotational frequency of the spindle motor M1,detected by the encoder E, tends to become different from the actualrotational frequency of the spindle securely holding a workpiece to bemachined, when a slip is caused in the transmission mechanism by, e.g.,the machining load during a turning process. In this case, in theelectronic-cam control on the basis of the rotational frequency of thespindle motor M1, the spindle and the tool rest are operated to performthe relative feed motion in accordance with the rotational frequency ofthe spindle motor M1 irrespective of the actual machining progress ofthe workpiece, which may cause deterioration of the machining accuracy.

To eliminate such a problem, a rotation detector D for detecting theactual rotational frequency of a spindle S, from which the pulse trainis acquired for the electronic-cam control, is advantageously used asthe spindle-pulse generating source, as shown in FIG. 5. In thisarrangement, a control device C operates and processes the transferpositions directed through the cam-reference data by using the pulsetrain acquired from the rotation detector D, and outputs a transfercommand based thereon so as to control the operation of a control axismotor M2. Therefore, even when the slip is caused in a transmissionmechanism T by, e.g., the machining load during a turning process, it isensured that the pulse train acquired from the rotation detector Dcorresponds to the actual rotational frequency of a workpiece W to bemachined. As a result, when the electronic-cam control on the basis of aspindle rotational frequency is performed, the relative feed motionbetween the spindle and the tool rest accurately matches to the actualmachining progress of the workpiece w, which makes it possible tomaintain a high machining accuracy.

It is also advisable to constitute at least one of the pluralpulse-train generating sources required for the electronic-cam controlas described above from an outside-pulse generating source generating apulse train irrespective of an operation of the automatically operatedlathe, such as a clock signal generator (not shown) installed within,e.g., a control device inherent in the automatically operated lathe or apersonal computer outside of the automatically operated lathe. In thisarrangement, the cam-reference data is processed by using a certainoutside pulse train (e.g., a clock pulse train) generated irrespectiveof the operating situation of the mechanically operative component ofthe automatically operated lathe.

As described with reference to the above machining sequence example,when the time-series allocation of the plural cam-reference data in thesequence of machining programs and/or the pulse-train generating sourceused in the processing step of each cam-reference data is designated onthe displacement diagrams, it is advantageous that the desireddisplacement diagram is displayed on a display screen provided, e.g., inassociation with the control device of the automatically operated lathe.In this case, as shown in FIG. 6A, a pulse-train generating source (apulse type) used for processing the second cam-reference data forinterruption may be directed by describing it inside a predeterminedblank as displayed, and a location where the second cam-reference datainterrupts may be directed by a screen picture such as an arrow, on thescreen displaying the displacement diagram of the first cam-referencedata in which a pulse-train generating source is previously determined.Alternatively, the location for the interruption may be directed byentering a numerical data, such as a cam rotation angle, the number ofpulse or a process number (e.g., a tool number).

As shown in FIG. 6B, it is possible to display the resultant compositedisplacement diagram on the screen in the same way. In the compositedisplacement diagram of FIG. 6B, when the cam-reference data isprocessed in a region (I) of cam rotation quantity, the cam rotationquantity is defined by the number of pulse (or a pulse number) countedin a pulse train generated from the first pulse-train generating source.Also, when the cam-reference data is processed in a region (II) of camrotation quantity, the cam rotation quantity is defined by a pulsenumber counted in a pulse train generated from the second pulse-traingenerating source.

It will be appreciated that the preparation of the above-describeddisplacement diagrams may be performed not only in the control devicepreviously installed in the automatically operated lathe, but also in anoutside computer.

Following is the description of the constitution of an automaticallyoperated lathe 10 (see FIG. 7) as well as of a control device 12 (seeFIG. 8) installed in the automatically operated lathe 10, each accordingto one embodiment of the present invention, and each capable of carryingout the automatically operated lathe controlling method according to theinvention. The automatically operated lathe 10 includes two spindles 16,18 and two tool rests 20, 22, intensively mounted on a common lathe bed14, and has a multifunctional arrangement capable of performing asimultaneous machining of different processes (e.g., anouter-diametrical turning and a boring) for an identical workpieceand/or a simultaneous machining for different workpieces by varioustools including a cutting tool 24 for a turning process, such as aturning tool or a drill, and a rotary tool 26 such as a milling cutter.

As shown in FIG. 7, the automatically operated lathe 10 includes a lathebad 14, a first spindle 16 mounted on the lathe bed 14 and having arotation axis 16 a, a first tool rest 20 mounted on the lathe bed 14 andcapable of holding a plurality of tools 24, 26 in parallel rows, asecond tool rest 22 mounted on the lathe bed 14 and capable of holding aplurality of tools 24, 26 in a circumferentially distributed manner, asecond spindle 18 mounted on the lathe bed 14 and having a rotation axis18 a parallel to the rotation axis 16 a of the first spindle 16 to becapable of oppositely facing the first spindle 16, and a control device12 for controlling the operation of the first and second spindles 16, 18as well as of the first and second tool rests 20, 22 on the lathe bed14.

The lathe bed 14 carries, independently, the first spindle 16, thesecond spindle 18, the first tool rest 20 and the second tool rest 22 ina respectively movable manner in a predetermined rectangular coordinatesystem.

The first spindle 16 is a main (or front-side) spindle which securelyholds a bar-shaped workpiece w to be machined (hereinafter referred toas a bar) supplied from an outside of the lathe and rotates therewith,and is rotatably supported within a first spindle stock 28 through abearing unit not illustrated. The first spindle 16 has a hollow tubularstructure, and is equipped at the front end region thereof with a chuck(not shown) capable of firmly and securely holding the bar W suppliedfrom the rear end region. The lathe bed 14 is equipped with a firstspindle drive mechanism 30 (FIG. 8) for linearly transferring the firstspindle stock 28 along a first feed-control axis (referred to as aZ1-axis) parallel to the rotation axis 16 a of the first spindle 16 in athree-axis rectangular coordinate system defined on the lathe bed 14.

The first spindle drive mechanism 30 is constituted from a Z1-axis drivesource (e.g., an AC servo motor) 32, as well as a Z1-axis guide member(e.g., a slide guide) and a feed screw unit (e.g., a ball screw), bothnot illustrated. Consequently, the first spindle 16 is capable oflinearly reciprocating along the first feed-control axis (Z1-axis)parallel to its own rotation axis 16 a, together with the first spindlestock 28, due to the operation of the first spindle drive mechanism 30.

The first spindle stock 28 is also equipped therein with a rotationdrive source 34 (FIG. 8), such as a built-in AC servo motor, forrotationally driving the first spindle 16. Also, the first spindle 16may have a rotation-angle control axis (referred to as a C1-axis), whichmakes it possible to perform various secondary machining processes atdesired positions on the end and/or circumferential surface of the bar Wsecurely held by the chuck, by using rotary tools 26 carried on thedesired tool rests 20, 22, due to an indexable positioning operation inthe C1-axis obtained by controlling the rotation drive source 34.

The lathe bed 14 is equipped, at a predetermined location spaced axiallyforward from the first spindle stock 28, with a guide bush 36 as anauxiliary support unit for supporting the bar W securely held in thefirst spindle 16 at a position near a leading end length to be machinedof the bar. The guide bush 36 is disposed coaxially relative to thefirst spindle 16 and supports the bar W in a centering manner so as toprevent the length to be machined of the bar from running-out during theturning process thereof.

The first tool rest 20 is disposed on the lathe bed 14 at a locationlaterally retreated from the guide bush 36 positioned axially forward ofthe first spindle 16. The lathe bed 14 is equipped with a first toolrest drive mechanism 38 (FIG. 8) for linearly transferring the firsttool rest 20 along a second feed-control axis (referred to as anX1-axis) parallel to the rotation axis 16 a of the first spindle 16(i.e., the first feed-control axis (Z1-axis)) in a three-axisrectangular coordinate system defined on the lathe bed 14. As shown inFIG. 9, the first tool rest drive mechanism 38 is capable of linearlytransferring the first tool rest 20 along a third feed-control axis(referred to as a Y1-axis) orthogonal to both the first feed-controlaxis (Z1-axis) and the second feed-control axis (X1-axis).

The first tool rest drive mechanism 38 is constituted from an X1-axisdrive source (e.g., an AC servo motor) 40, an X1-axis guide member(e.g., a slide guide) and a feed screw unit (e.g., a ball screw), bothnot illustrated, as well as a Y1-axis drive source (e.g., an AC servomotor) 42 (FIG. 9), a Y1-axis guide member (e.g., a slide guide) and afeed screw unit (e.g., a ball screw), both not illustrated.Consequently, the first tool rest 20 is capable of linearlyreciprocating along the second feed-control axis (X1-axis) and the thirdfeed-control axis (Y1-axis) due to the operation of the first tool restdrive mechanism 38.

The first tool rest 20 is a so-called flat turret tool rest capable ofholding a plurality of tools 24, 26 in parallel rows. Therefore, thefirst tool rest 20 is capable of transferring, along a designated toolpath, the cutting edge of the desired tool 24, 26 selected in anindexing manner by the Y1-axis motion of the first tool rest, due to thecooperation of the X1-axis feed motion of the first tool rest 20 and theabove-described Z1-axis feed motion of the first spindle 16 according tothe machining programs as described later. Consequently, it is possibleto machine the bar w securely held in the first spindle 16 into adesired shape by using desired tools 24, 26 on the first tool rest 20.

In the illustrated embodiment, the second tool rest 22 is disposed onthe lathe bed 14 at a location opposite to the first tool rest 20 inrelation to the rotation axis 16 a of the first spindle 16. The lathebed 14 is equipped with a second tool rest drive mechanism 44 (FIG. 8)for linearly transferring the second tool rest 22 along a fourthfeed-control axis (referred to as an X2-axis) orthogonal to the rotationaxis 16 a of the first spindle 16 (i.e., the first feed-control axis(Z1-axis)) and a fifth feed-control axis (referred to as a Z2-axis)parallel to the first feed-control axis (Z1-axis), respectively, in atwo-axis rectangular coordinate system defined on the lathe bed 14.

The second tool rest drive mechanism 44 is constituted from an X2-axisdrive source (e.g., an AC servo motor) 46, an X2-axis guide member(e.g., a slide guide) and a feed screw unit (e.g., a ball screw), bothnot illustrated, as well as a Z2-axis drive source (e.g., an AC servomotor) 48, a Z2-axis guide member (e.g., a slide guide) and a feed screwunit (e.g., a ball screw), both not illustrated. Consequently, thesecond tool rest 22 is capable of linearly reciprocating along thefourth feed-control axis (X2-axis) and the fifth feed-control axis(Z2-axis) due to the operation of the second tool rest drive mechanism44.

The second tool rest 22 is a so-called turret tool rest capable ofholding a plurality of tools 24, 26 in a circumferentially distributedmanner, and rotates in an indexing manner about a rotationallyindex-control axis (referred to as a TI axis) parallel to the Z2-axisdue to the operation of an index drive source 50 (e.g., an AC servomotor), as shown in FIG. 10. Therefore, the second tool rest 22 iscapable of transferring, along a designated tool path, the cutting edgeof the desired tool 24, 26 selected in an indexing manner by the TI-axisrotation of the second tool rest, due to the cooperation of the X2-axisfeed motion and the Z2-axis feed motion of the second tool rest 22according to the machining programs as described later. Consequently, itis possible to machine the bar W securely held in the first or secondspindle 16, 18 into a desired shape by using desired tools 24, 26 on thesecond tool rest 22.

The second spindle 18 is disposed on the lathe bed 14 at a locationaxially forward of the first spindle 16 or the guide bush 36 with therotation axis 18 a being parallel to the rotation axis 16 a of the firstspindle 16 so as to be capable of oppositely facing the guide bush in acoaxial manner. The second spindle 18 is an auxiliary (or rear-side)spindle which securely holds a bar W′ as a blank passed from the firstspindle 16 and rotates therewith, and is rotatably supported within asecond spindle stock 52 through a bearing unit not illustrated. Thesecond spindle 18 has a hollow tubular structure, and is equipped at thefront end region thereof with a chuck (not shown) capable of firmly andsecurely holding the bar W fed from the opposed guide bush 36.

The lathe bed 14 is equipped with a second spindle drive mechanism 54(FIG. 8) for linearly transferring the second spindle stock 52 along asixth feed-control axis (referred to as an X3-axis) orthogonal to thefirst feed-control axis (Z1-axis) of the first spindle 16 and a seventhfeed-control axis (referred to as a Z3-axis) parallel to the firstfeed-control axis (Z1-axis), respectively, in a two-axis rectangularcoordinate system defined on the lathe bed 14.

The second spindle drive mechanism 54 is constituted from an X3-axisdrive source (e.g., an AC servo motor) 56, an X3-axis guide member(e.g., a slide guide) and a feed screw unit (e.g., a ball screw), bothnot illustrated, as well as a Z3-axis drive source (e.g., an AC servomotor) 58, a Z3-axis guide member (e.g., a slide guide) and a feed screwunit (e.g., a ball screw), both not illustrated. Consequently, thesecond spindle 18 is capable of linearly reciprocating along the sixthfeed-control axis (X3-axis) and the seventh feed-control axis (Z3-axis),together with the second spindle stock 52, respectively, due to theoperation of the second spindle drive mechanism 54.

The second spindle stock 52 is also equipped therein with a rotationdrive source 60 (FIG. 8), such as a built-in AC servo motor, forrotationally driving the second spindle 18. Also, the second spindle 18may have a rotation-angle control axis (referred to as a C2-axis), whichmakes it possible to perform various secondary machining processes atdesired positions on the end and/or circumferential surface of the bar Wsecurely held by the chuck, by using rotary tools 26 carried on thesecond tool rest 22, due to an indexable positioning operation in theC2-axis obtained by controlling the rotation drive source 60.

The automatically operated lathe 10 is constructed so as toautomatically and respectively machine the bars W, W′ securely held inthe front-side spindle 16 and the rear-side spindle 18, by using thedesired tools 24, 26 in the two tool rests 20, 22 having the abovestructure, under the control of the control device 12. FIG. 8 shows theconstitution of the control device 12 for carrying out such an automaticmachining.

The control device 12 includes an input section 62, a display section64, an arithmetic control section 66 and a servo control section 68. Theinput section 62 includes a keyboard or a pointing device, notillustrated, and makes it possible for an operator to enter directionsand data in an interactive manner while referring various screensdisplayed in the display section 64. In the automatically operated lathe10, data (such as a tool selection, a product's shape and dimension, aspindle rotation frequency, a tool feed rate, etc.) required forcontrolling the operation of each of the first and second spindles 16,18 as well as the first and second tool rests 20, 22 are entered throughthe input section 62. The display section 64 includes a display unit,such as a CRT (cathode-ray tube) or an LCD (liquid crystal display), notillustrated, and displays data input images and/or prepared machiningprograms so as to permit an interactive entering operation by anoperator.

The arithmetic control section 66 includes a RAM (random access memory)70 and a ROM (read only memory) 72, both constituting a storage section,as well as a CPU (central processing unit) 74 constituting a processingsection. The various kinds of data entered through the input section 62are stored in the RAM 70 or the ROM 72 under the instructions from theCPU 74. The ROM 72 also previously stores a controlling program foroperating the first and second spindles 16, 18 as well as the first andsecond tool rests 20, 22. The CPU 74 outputs a controlling command onthe basis of the data stored in the RAM 70 or the ROM 72 to the servocontrol section 68 in accordance with a machining program preparedthrough a procedure as described later and the controlling programstored in the ROM 72.

The servo control section 68 includes a first spindle transfercontroller 76, a first spindle rotation controller 78, a first tool resttransfer controller 80, a second tool rest transfer controller 82, asecond spindle transfer controller 84 and a second spindle rotationcontroller 86. The first spindle transfer controller 76 operates, underthe command from the CPU 74, the Z1-axis drive source 32 of the firstspindle drive mechanism 30 so as to transfer the first spindle 16 alongthe Z1-axis together with the first spindle stock 28. The first spindlerotation controller 78 operates, under the command from the CPU 74, therotation drive source 34 so as to rotate the first spindle 16 on theC1-axis in the first spindle stock 28. In this respect, the high-speedrotation of the first spindle 16 for a turning process is controlledthrough another control circuit, not illustrated, on the basis of datasuch as a rotational frequency.

The first tool rest transfer controller 80 operates, under the commandfrom the CPU 74, either the X1-axis drive source 40 or the Y1-axis drivesource 42 of the first tool rest drive mechanism 38 so as to transferthe first tool rest 20 along the X1-axis or the Y1-axis. The second toolrest transfer controller 82 operates, under the command from the CPU 74,either the X2-axis drive source 46 or the Z2-axis drive source 48 of thesecond tool rest drive mechanism 44 so as to transfer the second toolrest 22 along the X2-axis or the Z2-axis.

The second spindle transfer controller 84 operates, under the commandfrom the CPU 74, either the X3-axis drive source 56 or the Z3-axis drivesource 58 of the second spindle drive mechanism 54 so as to transfer thesecond spindle 18 along the X3-axis or the Z3-axis. The second spindlerotation controller 86 operates, under the command from the CPU 74, therotation drive source 60 so as to rotate the second spindle 18 on theC2-axis in the second spindle stock 52. In this respect, the high-speedrotation of the second spindle 18 for a turning process is controlledthrough another control circuit, not illustrated, on the basis of datasuch as a rotational frequency.

It will be appreciated that the constitution of the control device 12 asshown by the block diagram of FIG. 8 corresponds to the constitution ofa conventional numerical controlled (NC) lathe. However, the controldevice 12 of the present invention is not limited to this block diagrambut may have various other constitutions.

The control device 12, constituting the above-described control system,adopts the characteristic features as described below, for carrying outthe automatically operated lathe controlling method according to theinvention so as to have the automatically operated lathe 10 fully exertthe multifunctional properties inherent therein and to enable thesequence of machining programs for the bars W, W′ to be surely performedunder the electronic-cam control system.

That is, the input section 62 permits an entering of each of a pluralityof target or transfer position data, required in a sequence of machiningprograms in connection with the first and second spindles 16, 18 and thefirst and second tool rests 20, 22 of the automatically operated lathe10, in the form of a cam-reference data directing a transfer position asa function of a cam rotation quantity. Also, the input section 62permits a designation of a pulse-train generating source for generatinga pulse train defining the cam rotation quantity as one component of thecam-reference data, with regard to each of the plural transfer positiondata, by selecting the pulse-train generating source from the pluralpulse-train generating sources as previously provided.

Particularly, in the control device 12, the input section 62 isstructured to permit the designation of the pulse-train generatingsource with regard to each of the plural transfer position data, inrelation to each of the plural control axes (X1, Y1, Z1, X2, Z2, X3, Z3)of the automatically operated lathe 10. In the input section 62, thepulse-train generating source should be suitably selected and designatedfor each of the plural processes performed through the sequence ofmachining programs, provided that the pulse train for processing thetransfer position data required for each control axis is surely andcontinuously acquired during the process concerned.

In this respect, in the automatically operated lathe 10, it is possibleto have the rotation drive sources 34, 60 of the first and secondspindle 16, 18 and the rotation drive source 88 (FIG. 9) of any rotarytool 26 functioned as the plural pulse-train generating sources whichare suitably selectable. In this case, it is advisable that the CPU 74of the control device 12 is arranged so as to use a pulse traingenerated from an encoder 90 (FIG. 7) provided in a built-in AC servomotor as a rotation drive source 34, 60 of the first or second spindle16, 18, or from an encoder 92 (FIG. 7) provided in an AC servo motor asa rotation drive source 88 of the rotary tool 26, for a rotation controlof spindle or tool concerned, as well as for processing thecam-reference data in the above-described electronic-cam control, asalready described with reference to FIG. 4. In this arrangement, the CPU74 operates and processes the transfer positions directed through thecam-reference data by using the pulse trains acquired from the desiredencoders 90, 92, and outputs a transfer command based thereon to theservo control section 68. Consequently, the operation of the respectiveaxis drive sources 32, 40, 42, 46, 48, 56, 58 of the respectivecontrol-axis drive mechanisms 30, 38, 44, 54 are controlled on the basisof the cam-reference data.

Moreover, in the automatically operated lathe 10, it is also possible topreviously provide a plurality of pulse-train generating sourcesconstituted from a spindle-pulse generating source including a rotationdetector 94 (FIG. 7) as described with reference to FIG. 5, and anoutside-pulse generating source such as a clock signal generator 96(FIG. 7) installed within the control device 12 or a clock signalgenerator 98 (FIG. 7) installed within a personal computer, etc.,outside of the automatically operated lathe.

The CPU 74 of the arithmetic control section 66 processes each of theplural transfer position data entered through the input section 62 inthe form of the cam-reference data, by using the pulse train generatedthrough the pulse-train generating source 90, 92, 94, 96, 98 designatedthrough the input section 62. Then, the CPU 74 generates a controlsignal for controlling a relative feed motion between the first andsecond spindles 16, 18 and the first and second tool rests 20, 22 in thesequence of machining programs, so as to output it to the servo controlsection 68.

Also, in the input section 62, it is possible to designate thetime-series allocation of the plural transfer position data in thesequence of machining programs, in relation to each of the pluralcontrol axes (X1, Y1, Z1, X2, Z2, X3, Z3) of the automatically operatedlathe 10. Thereby, plural processes performed on the basis of thecam-reference data processed by using different pulse-train generatingsources are arranged in the most suitable order. Accordingly, the CPU 74of the arithmetic control section 66 processes each of the pluraltransfer position data respectively entered in the form of thecam-reference data, in accordance with the time-series allocationdesignated through the input section 62, and generates a control signalfor controlling a relative feed motion between the first and secondspindles 16, 18 and the first and second tool rests 20, 22, so as tooutput it to the servo control section 68. In this manner, the pluralprocesses in the sequence of machining programs are performed in themost suitable order.

The display section 64 of the control device 12 is capable of displayingeach of the plural transfer position data, respectively entered throughthe input section 62 in the form of the cam-reference data, in the formof a displacement diagram representing a locus of transfer positions(e.g., a tool path). The input section 62 permits a designation of thetime-series allocation of the plural cam-reference data using differentpulse-train generating sources on any one displacement diagram displayedin the display section 64, as described with reference to FIG. 6A.

According to the above constitution, it is possible for the controldevice 12 to control the first spindle drive mechanism 30, the firsttool rest drive mechanism 38, the second tool rest drive mechanism 44and the second spindle drive mechanism 54 in a mutually associatedmanner, so as to carry out the sequence of machining programs for thebars W, W′ on the basis of the plural cam-reference data processed byusing different pulse-train generating sources.

One example of a machining sequence carried out through theabove-described sequence of machining programs is described below, withreference to FIG. 11. In the machining sequence example of FIG. 11, acutting tool (a turning tool) 24 carried on the first tool rest 20performs, as a first machining process, an outer-diametrical turningprocess to the bar W securely held in the first spindle 16, under thecooperation of the Z1-axis feed motion of the first spindle 16 and theX1-axis feed motion of the first tool rest 20. After theouter-diametrical turning process is finished, the rotation of the firstspindle 16 is halted, and the rotary tool 26 carried on the second toolrest 22 performs a lateral-surface drilling process to the bar Wsecurely held in the first spindle 16, under the X2-axis feed motion ofthe second tool rest 22.

After the lateral-surface drilling process is finished, the firstspindle 16 and the second spindle 18 are operated to rotate in highspeed in a synchronized manner, and in this state, the second spindle 18is operated to carry out the Z3-axis feed motion and the chuck providedtherein is operated to hold the leading end portion of the bar W. Then,a cutting tool (a turning tool) 24 carried on the first tool rest 20performs a parting process to the bar W securely held in both the firstand second spindles 16, 18, under the X1-axis feed motion of the firsttool rest 20, so as to separate the bar into a bar W′ as a blank and abar W being not machined. In this way, the workpiece to be machined ispassed or delivered from the first spindle 16 to the second spindle 18.In this respect, after the lateral-surface drilling process is finished,the second tool rest 22 is operated for indexing rotation, so as toposition a cutting tool (a drill) 24 used in the next machining processat a working location. Moreover, after the parting process is finished,the first tool rest 20 is shifted back to an initial position, and,after the delivery is finished, the first spindle 16 is also shiftedback to an initial position.

Next, the second spindle 18 is transferred to a position oppositelyfacing to the cutting tool (the drill) 24 carried on the second toolrest 22, under the cooperation of the X3-axis feed motion and theZ3-axis feed motion of the second spindle. In this position, the cuttingtool (the drill) 24 carried on the second tool rest 22 performs anend-surface drilling process to the bar W′ securely held in the rotatingsecond spindle 18, under the Z2-axis feed motion of the second tool rest22.

FIG. 11 illustrates a tool path of the cutting tool (the turning tool)24 carried on the first tool rest 20 by an arrow TP1. Also, a tool pathof the rotary tool 26 carried on the second tool rest 22 is illustratedby an arrow TP2. Moreover, a tool path of the cutting tool (the drill)24 carried on the second tool rest 22 is illustrated by an arrow TP3.

A plurality of transfer position data used in the above-describedexample of machining sequence will be described below with reference todisplacement diagrams shown in FIGS. 12 to 15.

Two displacement diagrams shown in FIG. 12 represent, as different camdiagrams, a cam-reference data for controlling the X1-axis feed motionof the first tool rest 20 and a cam-reference data for controlling theZ1-axis feed motion of the first spindle 16, from a condition where thecutting tool (the turning tool) 24 on the first tool rest 20 performsthe outer-diametrical turning process to the bar W securely held in thefirst spindle 16, to a condition where the tool performs the partingprocess to the bar W and thereafter is shifted back to the initialposition. In these displacement diagrams, the period of the pulse numberQ0 to Q3 corresponds to a cam single rotation in a control system forcontrolling the relative feed motion between the first spindle 16 andthe first tool rest 20 and, during this period, the first spindle 16 isin a condition of high-speed rotation. Accordingly, in thesedisplacement diagrams, a spindle-pulse generating source (e.g., theencoder 90 installed within the rotation drive source 34) generating apulse train corresponding to the rotation of the first spindle 16 isdesignated as the pulse-train generating source used for processing thecam-reference data.

As seen from two displacement diagrams of FIG. 12, during the period ofthe pulse number Q0 to Q1, the first spindle 16 and the first tool rest20 are operated to carry out the feed motions on the respective controlaxes (Z1-axis and X1-axis) in a synchronized manner on the basis of thecam-reference data. As a result, the cutting tool (the turning tool) 24is transferred along the tool path TP1 shown in FIG. 11, so as toperform the outer-diametrical turning process to the bar W. Also, duringthe period of the pulse number Q1 to Q2, the first spindle 16 is kept ata position PZ while the first tool rest 20 is operated to carry out theX1-axis feed motion on the basis of the cam-reference data. As a result,the cutting tool (the turning tool) 24 performs the parting process tothe bar W, and thereafter the first tool rest is shifted back to theinitial position. Then, during the period of the pulse number Q2 to QE,the first spindle 16 is operated to carry out the Z1-axis feed motion soas to be shifted back to the initial position, on the basis of thecam-reference data.

The displacement diagram shown in FIG. 13 represents, as a cam diagram,a cam-reference data for controlling the X2-axis feed motion of thesecond tool rest 22, during a condition where the rotary tool 26 on thesecond tool rest 22 performs the lateral-surface drilling process to thebar W securely held in the first spindle 16 as being halted. In thisdisplacement diagram, the period of the pulse number Q4 to Q5corresponds to a cam single rotation in a control system for controllingthe relative feed motion between the first spindle 16 and the secondtool rest 22, and, during this period, the rotation of the first spindle16 is halted. Accordingly, in this displacement diagram, a toll-pulsegenerating source (e.g., the encoder 92 installed within the rotationdrive source 88) generating a pulse train corresponding to the rotationof the rotary tool 26 is designated as the pulse-train generating sourceused for processing the cam-reference data.

As seen from the displacement diagram of FIG. 13, during the period ofthe pulse number Q4 to Q5, the second tool rest 22 is operated to carryout the feed motion on the control axis thereof (X2-axis) on the basisof the cam-reference data. As a result, the rotary tool 26 istransferred along the tool path TP2 shown in FIG. 11, so as to performthe lateral-surface drilling process on the bar W.

Two displacement diagrams shown in FIG. 14 represent, as different camdiagrams, a cam-reference data for controlling the Z3-axis feed motionof the second spindle 18 and a cam-reference data for controlling theX3-axis feed motion of the second spindle 18, from a condition where thesecond spindle 18 receives the bar WI from the first spindle 16 afterthe lateral-surface drilling process is finished, to a condition wherethe second spindle is transferred into the position oppositely facingthe cutting tool (the drill) 24 on the second tool rest 22. In thesedisplacement diagrams, the period of the pulse number Q6 to Q10corresponds to a cam single rotation in a control system for controllingthe relative feed motion between the first spindle 16 and the secondspindle 18, and, during this period, the first spindle 16 is in acondition of high-speed rotation. Accordingly, in these displacementdiagrams, a spindle-pulse generating source (e.g., the encoder 90installed within the rotation drive source 34) generating a pulse traincorresponding to the rotation of the first spindle 16 is designated asthe pulse-train generating source used for processing the cam-referencedata.

As seen from two displacement diagrams of FIG. 14, during the period ofthe pulse number Q6 to Q7, the second spindle 18 is operated to carryout the feed motion on one control axis (X3-axis), so as to be locatedat a position axially opposite to the first spindle 16 and to be kept atthis position, on the basis of the cam-reference data. Also, during theperiod of the pulse number Q7 through Q8 to Q9, the second spindle 18 isoperated to carry out the feed motion on the other control axis(Z3-axis) in a direction toward the first spindle 16, to securely holdthe bar W′ by the chuck, and to be kept in this condition, on the basisof the cam-reference data. In this respect, the second spindle 18 isbrought into a condition of high-speed rotation with the same speed asthe first spindle 16, before the chuck is operated to securely hold thebar We. Then, during the period of the pulse number Q9 to Q10, thesecond spindle 18 is operated to carry out the feed motion on theX3-axis and the Z3-axis in a synchronized manner, so as to betransferred to the position opposite to the cutting tool (the drill) 24on the second tool rest 22.

The displacement diagram shown in FIG. 15 represents, as a cam diagram,cam-reference data for controlling the Z2-axis feed motion of the secondtool rest 22, during a condition where the cutting tool (the drill) 24on the second tool rest 22 performs the end-surface drilling process tothe bar WI securely held in the second spindle 18 rotating in ahigh-speed. In this displacement diagram, the period of the pulse numberQ11 to Q12 corresponds to a cam single rotation in a control system forcontrolling the relative feed motion between the second spindle 18 andthe second tool rest 22, and, during this period, the rotation of thefirst spindle 16 is halted while the second spindle 18 is in a conditionof high-speed rotation. Accordingly, in this displacement diagram, aspindle-pulse generating source (e.g., the encoder 90 installed withinthe rotation drive source 60) generating a pulse train corresponding tothe rotation of the second spindle 18 is designated as the pulse-traingenerating source used for processing the cam-reference data.

As seen from the displacement diagram of FIG. 15, during the period ofthe pulse number Q11 to Q12, the second tool rest 22 is operated tocarry out the feed motion on the control axis thereof (Z2-axis) on thebasis of the cam-reference data. As a result, the cutting tool (thedrill) 24 is transferred along the tool path TP3 shown in FIG. 11, so asto perform the end-surface drilling process to the bar W′.

The displacement diagrams (or single-axis diagrams) in relation to therespective control axes used in the above-described machining sequenceexample can be displayed on the display screen in the display section 64of the control device 12. In this respect, it is possible to display, asa compound-axis displacement diagram, the plural displacement diagramsassociated with a common pulse-train generating source used forprocessing the cam-reference data, by composing these diagrams on asingle screen. More concretely, the two displacement diagramsrepresenting the transfer position data for the first spindle 16(Z1-axis) and the first tool rest 20 (X1-axis) shown in FIG. 12 as wellas the two displacement diagrams representing the transfer position datafor the second spindle 18 (Z3-axis, X3-axis) shown in FIG. 14 designatethe first spindle-pulse generating source as the pulse-train generatingsource, so that it is possible to display these displacement diagrams onthe screen as a compound-axis displacement diagram, as shown in FIG. 16,by composing these diagrams. It will be appreciated that, in thecompound-axis displacement diagram of FIG. 16, the pulse numbers Q0, Q1,Q2 and Q3 in the Z1-axis/X1-axis displacement diagram respectivelyconform to the pulse numbers Q6, Q8, Q9 and Q10 in the Z3-axis/X3-axisdisplacement diagram, whereby it is possible to easily comprehend thesynchronization between these control axes.

Furthermore, it is possible, on the compound-axis displacement diagramof FIG. 16, to direct the information of an interruption by the twodisplacement diagrams representing the transfer position data of thesecond tool rest 22 (X2-axis, Z2-axis) shown in FIGS. 13 and 15.Concerning the interruption information, pulse-train generating sourcesused for processing the plural transfer position data for interruptionmay be designated by describing it on the screen or selecting it from apreviously provided group as displayed, and a location where thesetransfer position data interrupts may be designated by a screen picturesuch as an arrow, or by entering a numerical data, such as a camrotation angle, the number of pulse or a process number (e.g., a toolnumber), as already described with reference to FIG. 6A.

As shown in FIG. 16, in the above-described machining sequence example,first, on the screen displaying the compound-axis displacement diagramrelating to Z1-axis, X1-axis, Z3-axis and X3-axis in which “a firstspindle-pulse generating source” is previously designated as apulse-train generating source, the interruption by the displacementdiagram relating to X2-axis is designated at a location of the pulsenumber Q1 (Q8), and “a tool-pulse generating source” is designated as apulse-train generating source for an arithmetic base of this X2-axisdisplacement diagram. Next, on the same screen, the interruption by thedisplacement diagram relating to Z2-axis is designated at a location ofthe pulse number Q3 (Q10), and “a second spindle-pulse generatingsource” is designated as a pulse-train generating source for anarithmetic base of this Z2-axis displacement diagram.

FIG. 17 shows a compound-axis displacement diagram relating to all ofthe control axes in a state after the interruption information isdirected. On the basis of this compound-axis displacement diagram, themachining sequence example as shown in FIG. 11 is effectively performedas described below.

First, during the pulse number R0 (corresponding to Q0 and Q6 in FIG.16) to R1 (corresponding to Q1 and Q8 in FIG. 16), the outer-diametricalturning process to the bar w by the cutting tool (the turning tool) 24on the first tool rest 20 and the preparation operation of the bardelivery process by the second spindle 18 are performed by using thefirst spindle-pulse generating source (I). Then, just at the pulsenumber R1, the feed motions of the first spindle 16 and the first toolrest 20 are halted. During the pulse number R1 (corresponding to Q4 inFIG. 13) to R2 (corresponding to Q5 in FIG. 13), the lateral-surfacedrilling process on the bar W by the rotary tool 26 on the second toolrest 22 is performed by using the tool-pulse generating source (II).

Successively, during the pulse number R2 (corresponding to Q1 and Q8 inFIG. 16) to R3 (corresponding to Q3 and Q10 in FIG. 16), the partingprocess of the bar W by the cutting tool (the turning tool) 24 on thefirst toll rest 20, the bar delivery process from the first spindle 16to the second spindle 18, and the preparation operation of theend-surface machining by the second spindle 18 are performed by usingthe first spindle-pulse generating source (I). Finally, during the pulsenumber R3 (corresponding to Q11 in FIG. 15) to RE (corresponding to Q12in FIG. 15), the end-surface drilling process to the bar W′ by thecutting tool (the drill) 24 on the second tool rest 22 is performed byusing the second spindle-pulse generating source (III). In this manner,one machining cycle is completed.

Incidentally, when the bar delivery process is performed in theabove-described machining sequence example, it is advantageous that thestart time of the Z3-axis feed motion of the second spindle 18 to beshifted toward the first spindle 16 is determined at such a time as toensure a best efficiency in a correlation with the operation of thefirst spindle 16, from the viewpoint of reducing a working time requiredto a single machining cycle. In the conventional NC lathe, this type oftiming is generally relatively difficult, and has tended to rely on anoperator's experience or skill. Contrary to this, in the automaticallyoperated lathe 10 in which the control device 12 is installed, it ispossible to significantly easily perform this type of timing on thedisplacement diagram.

More concretely, when the compound-axis displacement diagram of FIG. 16is prepared, it is advisable that the displacement diagram representingthe Z1-axis feed motion of the first spindle 16 is combined with thedisplacement diagram representing the Z3-axis feed motion of the secondspindle 18 in such a manner as to accurately place the coordinate of thepulse number Q1 and the coordinate of the pulse number Q8 at theidentical pulse number. To this end, the input section 62 of the controldevice 12 is preferably constituted to permit a relative positionbetween the plural displacement diagrams, for which the commonpulse-train generating source is designated, to be adjusted by shiftingthem relative to each other on the display screen of the display section64. The positional adjustment of the displacement diagrams may beperformed by a screen picture such as an arrow (so-called a dragoperation), or by entering a numerical data, such as a cam rotationangle, the number of pulse or a process number (e.g., a tool number), inthe same way as the designation of the location to be interrupted, asalready described.

According to this arrangement, it is ensured that the start time of theZ3-axis feed motion of the second spindle 18 to be shifted toward thefirst spindle 16 is automatically determined at a most efficient time sothat the first spindle 16 and the second spindle 18 simultaneously reacha bar delivery position. Consequently, the idle time of the feed motionof each spindle 16, 18 is eliminated, and the working time required tothe single machining cycle is reduced.

While the present invention has been described with reference to thepreferred embodiments thereof, it will be understood that the inventionis not restricted to those embodiments and that various changes andmodifications may be made without departing from the disclosure of theclaims.

What is claimed is:
 1. A method for controlling an automaticallyoperated lathe provided with at least one spindle and at least one toolrest, comprising: providing each of a plurality of transfer positiondata required in a sequence of machining programs in connection withsaid at least one spindle and said at least one tool rest in a form of acam-reference data directing a transfer position as a function of a camrotation quantity; providing a plurality of pulse-train generatingsources, each of which generates any pulse train; designating, withregard to each of said plurality of transfer position data, apulse-train generating source for generating a pulse train defining saidcam rotation quantity as one component of said cam-reference data, saidpulse-train generating source being selected from said plurality ofpulse-train generating sources; and processing each of said plurality oftransfer position data provided in the form of said cam-reference databy using said pulse train generated through said pulse-train generatingsource as designated, to control a relative feed motion between said atleast one spindle and said at least one tool rest in said sequence ofmachining programs.
 2. A method for controlling, as set forth in claim1, wherein said at least one spindle and said at least one tool rest arecapable of performing a relative feed motion along a plurality ofcontrol axes, and wherein the step of designating said pulse-traingenerating source includes designating said pulse-train generatingsource with regard to each of said plurality of transfer position datain relation to each of said plurality of control axes.
 3. A method forcontrolling, as set forth in claim 1, further comprising a step ofdesignating a time-series allocation of said plurality of transferposition data in said sequence of machining programs, wherein the stepof processing said transfer position data includes processing, inaccordance with said time-series allocation as designated, each of saidplurality of transfer position data provided in the form of saidcam-reference data.
 4. A method for controlling, as set forth in claim1, further comprising a step of showing, in a form of a displacementdiagram, each of said plurality of transfer position data provided inthe form of said cam-reference data.
 5. A method for controlling, as setforth in claim 4, wherein the step of designating said pulse-traingenerating source includes designating, in association with saiddisplacement diagram, said pulse-train generating source with regard toeach of said plurality of transfer position data.
 6. A method forcontrolling, as set forth in claim 4, further comprising a step ofdesignating a time-series allocation of said plurality of transferposition data in said sequence of machining programs on saiddisplacement diagram, wherein the step of processing said transferposition data includes processing, in accordance with said time-seriesallocation as designated on said displacement diagram, each of saidplurality of transfer position data provided in the form of saidcam-reference data.
 7. A method for controlling, as set forth in claim6, wherein said at least one spindle and said at least one tool rest arecapable of performing a relative feed motion along a plurality ofcontrol axes, and wherein the step of designating said time-seriesallocation includes designating, on said displacement diagram, asynchronization between said plurality of transfer position data forrespectively operationally controlling said plurality of control axes.8. A method for controlling, as set forth in claim 1, wherein saidplurality of pulse-train generating sources include a spindle-pulsegenerating source generating a pulse train corresponding to a rotationof said at least one spindle.
 9. A method for controlling, as set forthin claim 1, wherein said plurality of pulse-train generating sourcesinclude an outside-pulse generating source generating a pulse trainirrespective of an operation of the automatically operated lathe.
 10. Anautomatically operated lathe, comprising: a lathe bed; at least onespindle mounted on said lathe bed; at least one tool rest mounted onsaid lathe bed; a control device for controlling an operation of said atleast one spindle and said at least one tool rest on said lathe bed; anda plurality of pulse-train generating sources, each of which generatesany pulse train; said control device including: an input sectionpermitting an entering of each of a plurality of transfer position datarequired in a sequence of machining programs in connection with said atleast one spindle and said at least one tool rest in a form of acam-reference data directing a transfer position as a function of a camrotation quantity, and permitting a designation of a pulse-traingenerating source for generating a pulse train defining said camrotation quantity as one component of said cam-reference data, withregard to each of said plurality of transfer position data, saidpulse-train generating source being selected from said plurality ofpulse-train generating sources; and a processing section processing eachof said plurality of transfer position data entered through said inputsection in the form of said cam-reference data by using said pulse traingenerated through said pulse-train generating source designated throughsaid input section, to thereby generate a control signal for controllinga relative feed motion between said at least one spindle and said atleast one tool rest in said sequence of machining programs.
 11. Anautomatically operated lathe, as set forth in claim 10, wherein said atleast one spindle and said at least one tool rest are capable ofperforming a relative feed motion along a plurality of control axes onsaid lathe bed, and wherein said input section of said control devicepermits a designation of said pulse-train generating source with regardto each of said plurality of transfer position data in relation to eachof said plurality of control axes.
 12. An automatically operated lathe,as set forth in claim 10, wherein said input section of said controldevice permits an designation of a time-series allocation of saidplurality of transfer position data in said sequence of machiningprograms, and wherein said processing section of said control deviceprocesses, in accordance with said time-series allocation designatedthrough said input section, each of said plurality of transfer positiondata entered in the form of said cam-reference data through said inputsection.
 13. An automatically operated lathe, as set forth in claim 10,wherein said control device further includes a display sectiondisplaying, in a form of a displacement diagram, each of said pluralityof transfer position data entered through said input section in the formof said cam-reference data.
 14. An automatically operated lathe, as setforth in claim 13, wherein said input section of said control devicepermits a designation of said pulse-train generating source with regardto each of said plurality of transfer position data, in association withsaid displacement diagram displayed in said display section.
 15. Anautomatically operated lathe, as set forth in claim 13, wherein saidinput section of said control device permits a designation of atime-series allocation of said plurality of transfer position data insaid sequence of machining programs on said displacement diagramdisplayed in said display section, and wherein said processing sectionof said control device processes, in accordance with said time-seriesallocation as designated on said displacement diagram, each of saidplurality of transfer position data entered in the form of saidcam-reference data through said input section.
 16. An automaticallyoperated lathe, as set forth in claim 15, wherein said at least onespindle and said at least one tool rest are capable of performing arelative feed motion along a plurality of control axes on said lathebed, and wherein said input section of said control device permits adesignation of a synchronization between said plurality of transferposition data for respectively operationally controlling said pluralityof control axes, on said displacement diagram displayed in said displaysection.
 17. An automatically operated lathe, as set forth in claim 10,wherein said plurality of pulse-train generating sources include aspindle-pulse generating source generating a pulse train correspondingto a rotation of said at least one spindle.
 18. An automaticallyoperated lathe, as set forth in claim 10, wherein said plurality ofpulse-train generating sources include an outside-pulse generatingsource generating a pulse train irrespective of an operation of theautomatically operated lathe.
 19. A control device for use in anautomatically operated lathe provided with at least one spindle and atleast one tool rest, comprising: an input section permitting an enteringof each of a plurality of transfer position data required in a sequenceof machining programs in connection with said at least one spindle andsaid at least one tool rest in a form of a cam-reference data directinga transfer position as a function of a cam rotation quantity, andpermitting a designation of a pulse-train generating source forgenerating a pulse train defining said cam rotation quantity as onecomponent of said cam-reference data, with regard to each of saidplurality of transfer position data, said pulse-train generating sourcebeing selected from a plurality of pulse-train generating sources aspreviously provided; and a processing section processing each of saidplurality of transfer position data entered through said input sectionin the form of said cam-reference data by using said pulse traingenerated through said pulse-train generating source designated throughsaid input section, to thereby generate a control signal for controllinga relative feed motion between said at least one spindle and said atleast one tool rest in said sequence of machining programs.
 20. Acontrol device, as set forth in claim 19, wherein said input sectionpermits an designation of a time-series allocation of said plurality oftransfer position data in said sequence of machining programs, andwherein said processing section processes, in accordance with saidtime-series allocation designated through said input section, each ofsaid plurality of transfer position data entered in the form of saidcam-reference data through said input section.
 21. A control device, asset forth in claim 19, further comprising a display section displaying,in a form of a displacement diagram, each of said plurality of transferposition data entered through said input section in the form of saidcam-reference data.
 22. A control device, as set forth in claim 21,wherein said input section permits a designation of said pulse-traingenerating source with regard to each of said plurality of transferposition data, in association with said displacement diagram displayedin said display section.
 23. A control device, as set forth in claim 21,wherein said input section permits a designation of a time-seriesallocation of said plurality of transfer position data in said sequenceof machining programs on said displacement diagram displayed in saiddisplay section, and wherein said processing section processes, inaccordance with said time-series allocation as designated on saiddisplacement diagram, each of said plurality of transfer position dataentered in the form of said cam-reference data through said inputsection.